Aluminium alloy and article made therefrom



April 6, 1937. H. STAEUDEL ET AL 2,076,281

ALUMINIUM ALLOY AND ARTICLE MADE THEREFROM Filed March 28, 1935 Patented Apr. 1937 PATENT OFFICE 2,076,281 ALUMINIUM ALLOY AND Aa'rrcm MADE mncmom Hans Steudel and Heinz Wiechell, mlLt'Germany,

Junkers Flugaeug-und assignors, by mesne I I -Motorenwerke Aktiengesellschatt, Dessau, Germany Application March 28, 1935, Serial No. 13,431

4 Claims.

Our invention relates to aluminium alloys containing copper and iron and to articles made from such alloys. It has for its object to provide an alloy of the kind described which is particularly 5 suitable for use in machine parts or bearings bushings,

and iron balance to 100.

5 4 to 15 per cent Fe,

5 a very high specific strain,

cation supporting rotatory or oscillatory parts of machinery and for other purposes.

Aluminium alloys containing copper and iron have already been used in the manufacture of sleeves, guides, pistons and other parts of machinery subject to sliding motion. The compositions of these alloys are illustrated by the accompanying drawing which shows the compositions of alloys containing aluminium, copper by means of the conventional triangular diagram, in which the alloy composition represented by any given point on the diagram may be determined by drawing lines through said point parallel to two of the three sides of the triangle, which are divided up into percentages, as shown in the drawing. The two points .at which these parallel lines intersect the two sides of the triangle, determine in a well known manner the percentages of two components, while the percentage of the third component results as of the prior art are comprised within the triangle 1 forming part of the diagram shown in the drawing affixed to this specification and forming part thereof, this triangle being confined between the points Al, A1201). and T of the diagram.

In contradistinction to these alloys the alloys bounded by the triangle 2, which may be assumed theoreticallyto consist of primary AlzFe,

pound T between A12Cll and lilaFe) and of a tertiarily separated ground mass, rich in aluminium with mixed 'crystals of Al and with eutectic AlaFe, with the only exception of alloys containing a very low percentage (up to about 8 per cent) Cu and (up to about 4 per cent) Fe, 'were hitherto regarded as practically useless.

Our investigation of alloys of this type containing about 9 to 22 per cent Cu'and about the rest being A1, with a view to their suitability as a material for sliding bearings etc. has now shown that they possess V surprisingly favorable properties in this respect, being capable of withstanding, without seizing, which is a multiple or that shown by the customary bearing metals.

We believe these surprislng properties to be explainable by the assumption that the difiusion phenomena which are checked by the solidifiof the cast alloy, form a hindrance to the The compositions of the alloys of secondary peritecticum (i. e. a ternary comless intensive Germany November 22, 1934 formation of the secondary peritectic, while favoring the formation of a ternary eutectic of AhCu, T and mixed crystals of Al. As ascertained by running tests, this ternary eutectic ap pears to be capable of retaining the oil film in 5 such manner that it is not broken even under high specific pressures on the bearing.

The characteristic feature of the new material is the content of primary crystals of AlaFe forming hard bearing crystals and of ternary eutectic in a ground mass of minlum. Q

The region, shown in the drawing by hatching, which encloses the alloys according to this invention, which contain, besides aluminium, ranging from about 63 to 88 per cent, from 9 to 22 per cent Cu and from 4 to 15 per cent Fe, lies in the field marked 2 of the diagram, which is confined between the points Al, AlaFe (59% Al+4l% Fe) and T (being the ternary compound containing about 48% Al, 44% Cu and 8% Fe).

We have found an alloy containing about 15 per cent Cu and about 6 per cent Fe to be particularly suitable for sliding bearings.

An alloy containing about l0'per cent Cu and about 5 per cent Fe, while being very suitable for the same purpose, is somewhat softer than the alloy mentioned irrthe first place.

An alloy containing about 20 per cent Cu and about 5 per cent Fe was found to be somewhat harder than the first named alloy.

An alloy containing about 10 per cent Cu and about '7 per cent Fe is superior to the first named alloy as to running properties, but presents slighii difilculties in casting.

mixed crystals rich in alu- 12 per cent Fe has still better running properties.

Obviously the requirements will be different in each individual case, bearings running under high specific load requiring as a rule slightly harder metals, while on the other hand the properties of the shafts or spindlessupported in the bearings (whether formed with soft or hardened surfaces, whether being rigid-or subject to certain changes of form inoperation) :fiquire diflerent. bearing metals. Therefore one oy may be the best for one purpose, while being less suitable tor others. a

The process of solidification of the cast metal which considerably influences the structure, may be varied in a well known manner by a more on abduction of heat, for instance by chill casting,- to yield the structure most suitable for the purpose in view The term uminium used in the specification 2 andin-theioilowingclaimsislntendedtoincluda' notonlypumaluminimbutalscametalconitainingtheimpuriiiesoicommereialaluminium or small amounts 01' other impurities.

Various changes may bemadeiin the details disclosed in the foregoing, specification without deparflng Irom the invention or sacrificing the advantages thereof.

'Inthe dalmsammedtothisspeciflcation no Selection of any particular modification of the vention isintended to'the exclusion-of other thereof and the right to subseqnently make claim in the present application to an tion not covered by these claims is iielmesslyrcaerved.

Weclaimz- 1, An aluminium alloy consisting of from 9 to 2percentCuandIrom4to15percentFe,with abalaneealuminimn; said alloybeing character- HANS S'I'EUDEL.

HEINZ 

